Malaria caused by Plasmodium vivax threatens over 2 billion people globally and sickens tens of millions annually. Radical cure for P. vivax malaria includes therapy aimed both at the acute attack (blood schizontocidal) and against future attacks (hypnozoitocidal). The only hypnozoitocide available are 8- aminoquinolines such as primaquine or tafenoquine. However, clinicians often do not prescribe 8- aminoquinolines due to the high prevalence (8%) of individuals with various levels of inherited Glucose-6- phosphate dehydrogenase (G6PDH) deficiencies, because these drugs can cause life-threatening acute hemolytic anemia in patients with moderate to severe G6PDH deficits. There is an urgent need to quantify both Hgb and G6PDH for patients stricken with malaria or prior to the administration of 8-aminoquinilones. All current quantitative methods for G6PDH determination are laboratory based spectrophotometric methods, requiring diluents, reagents, pipettes and trained personnel. There are currently no commercially available point-of-care (POC) tests that can quantify both Hgb and G6PDH directly from a finger-stick sample. Developing a robust, quantitative assay for field use in low resource areas is a high priority for overall malaria control and elimination. In this proposal, In Vitro Diagnostic Systems (IVDS) will establish the feasibility of developing a POC test, the PreQuine Test, in which Hgb and G6PDH levels can be quantitated simultaneously from a 30 ?L blood stick sample. In pilot studies, we have successfully assessed Hgb and G6PDH levels using independent test strips. To develop a dual Hgb and G6PDH test strip, we propose develop a lysing protocol to maximize liberation of Hgb and G6PDH from blood samples (Aim 1), optimize Hgb and G6PDH assay conditions (Aim 2) and then combine the Hgb and G6PDH assays into a single test strip (Aim 3). The PreQuine Test results will be compared to results obtained with a calibrated hand-held meter; demonstration of concordance of the results from the PreQuine Test strip and calibrated meter to reference samples will indicate success. In Phase II, we will establish real-time and long-term stability of the PreQuine Test, implement a meter temperature compensation program, conduct pre-clinical testing as well as field testing, and use NCLIS guidelines for performance testing. The ability to identify G6PDH deficient individuals using a rapid POC test and also to monitor patients for G6PDH levels and Hgb levels during therapy would have great impact on malaria treatment strategies.